The hanging of the ‘witches’ in Newcastle upon Tyne in 1650.
Photograph: Getty Images

It was a terrifying phenomenon that continues to cast a shadow over certain parts of Europe even today. The great age of witch trials, which ran between 1550 and 1700, fascinates and repels in equal measure. Over the course of a century and a half, 80,000 people were tried for witchcraft and half of them were executed, often burned alive.

And then trials disappeared almost completely.

Their appearance was all the more strange because between 900 and 1400 the Christian authorities had refused to acknowledge that witches existed, let alone try someone for the crime of being one. This was despite the fact that belief in witches was common in medieval Europe, and in 1258 Pope Alexander IV had to issue a canon to prevent prosecutions.

But by 1550 Christian authorities had reversed their position, leading to a witch-hunt across Christendom. Many explanations have been advanced for what drove the phenomenon. Now new research suggests there is an economic explanation, one that has relevance to the modern day.

Economists Peter Leeson and Jacob Russ of George Mason University in Virginia argue that the trials reflected “non-price competition between the Catholic and Protestant churches for religious market share”.

As competing Catholic and Protestant churches vied to win over or retain their followers, they needed to make an impact – and witch trials were the battleground they chose. Or, as the two academics put it in their paper, to be published in the new edition of the Economic Journal: “Leveraging popular belief in witchcraft, witch-prosecutors advertised their confessional brands’ commitment and power to protect citizens from worldly manifestations of Satan’s evil.”

They reach their conclusion after drawing on analyses of new data covering more than 43,000 people tried for witchcraft in 21 European countries.

The data shows that witch-hunts took off only after the Reformation in 1517, following the rapid spread of Protestantism. Leeson and Russ argue that, for the first time in history, the Reformation presented large numbers of Christians with a religious choice: stick with the old church or switch to the new one. “And when churchgoers have religious choice, churches must compete,” they say.

The phenomenon reached its zenith between 1555 and 1650, the years when there was “peak competition for Christian consumers”, evidenced by the Catholic Counter-Reformation, during which Catholic officials pushed back against Protestant successes in converting Catholics to the new ways of worshipping throughout much of Europe.

The new analysis suggests that the witch craze was most intense where Catholic-Protestant rivalry was strongest. Churches picked key regional battlegrounds, they say, much like the Democrat and Republican parties in the US now focus on key states during the presidential election.

This explains why Germany, ground zero for the Reformation, laid claim to nearly 40% of all witchcraft prosecutions in Europe. Scotland, where different strains of Protestantism were in competition, saw the second highest level of witch-hunts, with a total of 3,563 people tried.

“In contrast, Spain, Italy, Portugal and Ireland – each of which remained a Catholic stronghold after the Reformation and never saw serious competition from Protestantism – collectively accounted for just 6% of Europeans tried for witchcraft,” Russ observes.

By around 1650, however, the witch frenzy began its precipitous decline, with prosecutions for witchcraft virtually vanishing by 1700. Leeson and Russ attribute this to the Peace of Westphalia, a series of treaties in 1648, which brought a close to the 30 years’ war and ended decades of religious warfare in Europe.

But the use of terror to impress a message on the population has not abated, they suggest. “The phenomenon we document – using public trials to advertise superior power along some dimension as a competitive strategy – is much broader than the prosecution of witches in early modern Europe,” Leeson says. “It appears in different forms elsewhere in the world at least as far back as the ninth century, all the way up to the 20th and Stalin’s show trials’ in the Soviet Union.”